Method for providing relational decentralized identifier service and blockchain node using the same

ABSTRACT

A method for providing a relational DID (decentralized identifier) service is provided. The method includes steps of: if a specific entity&#39;s device broadcasts to a blockchain network a request for registration of relational information which represents a relation between a specific entity&#39;s DID and another entity&#39;s DID and is set by another entity and confirmed by a specific entity, a blockchain node in the blockchain network (i) verifying the request and registering the relational information in the blockchain network as corresponding to the specific entity&#39;s DID and said another entity&#39;s DID or (ii) transmitting the request to an identity contract registered in the blockchain network, to allow the identity contract to verify the request and to register the relational information in the blockchain network as corresponding to the specific entity&#39;s DID and said another entity&#39;s DID.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Application No.10-2020-0076079, filed Jun. 22, 2020, which claims priority to KoreanProvisional Application No. 10-2019-0084088, filed Jul. 11, 2019, bothdisclosures which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a method for providing a relationaldecentralized identifier service and a blockchain node using the same;and more particularly, to the method for providing the relationaldecentralized identifier service by referring to relations amongentities and the blockchain node using the same.

BACKGROUND OF THE DISCLOSURE

In general, an ID is mapped onto personal information unique to anindividual.

For example, an email address aaa@gmail.com is a Google ID, and this IDis mapped onto the personal information such as its user's name, phonenumber, etc., and stored in the Google user database.

However, due to its centralized nature of the conventional IDs, leakageof the personal information caused by server hacking is frequent.Further, companies do not compensate their users for the collectedpersonal information and its usage.

As a solution for such a conventional centralized management system,decentralized identifiers (DIDs) have been developed as a self-sovereignidentity management technology.

For example, a DID such as did:meta:xxx is mapped onto personalinformation (PI) of an individual and stored in a user device, and thePI is verified by a third party, such as a certificate authority, thenthe PI is mapped onto the DID as a verifiable credential (VC) and storedin the user device or a VC repository, for example, an identity hubwhich is a public storage.

Although each entity who/which uses the DID can prove itself by usingthe DID and the VC, it cannot prove its relations with other entitieseven when using the DID as such.

SUMMARY OF THE DISCLOSURE

It is an object of the present disclosure to solve all theaforementioned problems.

It is another object of the present disclosure to prove relations amongentities.

It is still another object of the present disclosure to provide variousservices using the relations among the entities.

In accordance with one aspect of the present disclosure, there isprovided a method for providing a relational DID (decentralizedidentifier) service, including steps of: (a) if a request forregistration of relational information is broadcast from a specificentity's device to a blockchain network, wherein the relationalinformation represents information on a relation between a specificentity's DID of a specific entity and another entity's DID of anotherentity and wherein the relational information is set by said anotherentity and confirmed by the specific entity, a blockchain node in theblockchain network performing or supporting another device to performone of (i) a process of verifying the request for the registration ofthe relational information and (ii) a process of transmitting therequest for the registration of the relational information to anidentity contract registered in the blockchain network, to thereby allowthe identity contract to verify the request for the registration of therelational information; and (b) the blockchain node performing orsupporting another device to perform one of (i) a process of registeringthe relational information in the blockchain network as corresponding tothe specific entity's DID and said another entity's DID if the requestfor the registration of the relational information is determined asverified by the blockchain node, and (ii) a process of allowing theidentity contract to register the relational information in theblockchain network as corresponding to the specific entity's DID andsaid another entity's DID if the request for the registration of therelational information is determined as verified by the identitycontract.

As one example, the method further includes a step of: (c) if a requestfor the relational information is acquired from a service providingserver in response to a request for a service transmitted from thespecific entity's device wherein the service is accessible with saidanother entity's DID or if a request for DID public information isacquired from a resolving server in response to a request for a DIDdocument from the service providing server, wherein the request for theDID document is at least one of a request for a specific entity's DIDdocument and a request for another entity's DID document, wherein theDID public information includes at least one of specific entity's publicinformation and another entity's public information, wherein thespecific entity's public information is registered in the blockchainnetwork as corresponding to the specific entity's DID and includes therelational information and a specific entity's public key correspondingto the specific entity's DID, and wherein said another entity's publicinformation is registered in the blockchain network as corresponding tosaid another entity's DID and includes the relational information andanother entity's public key corresponding to said another entity's DID,the blockchain node performing or supporting another device to perform(1) one of (i) in response to the request for the relational informationfrom the service providing server, (i-1) a process of acquiring therelational information from the blockchain network by referring to thespecific entity's DID or said another entity's DID or a process ofallowing the identity contract to acquire the relational informationfrom the blockchain network by referring to the specific entity's DID orsaid another entity's DID, and (i-2) a process of transmitting therelational information to the service providing server, and (ii) inresponse to the request for the DID public information from theresolving server, (ii-1) a process of acquiring the DID publicinformation from the blockchain network by referring to at least one ofthe specific entity's DID and said another entity's DID or a process ofallowing the identity contract to acquire the DID public informationfrom the blockchain network by referring to at least one of the specificentity's DID and said another entity's DID, and (ii-2) a process ofallowing the resolving server to modify the DID public information intothe DID document and thus to transmit the DID document to the serviceproviding server, and as a result, (2) a process of allowing the serviceproviding server to (i) confirm a relation between the specific entity'sDID and said another entity's DID by referring to one of the relationalinformation acquired from the blockchain node and the relationalinformation acquired from the DID document, and (ii) if the relationbetween the specific entity's DID and said another entity's DID isconfirmed by using the relational information, provide the servicecorresponding to said another entity's DID to the specific entity'sdevice.

As one example, the request for the service transmitted from thespecific entity's device includes a specific entity's signature valuecreated by encrypting the request for the service with a specificentity's private key corresponding to the specific entity's DID, andwherein, if a request for the specific entity's public key correspondingto the specific entity's DID is acquired from the service providingserver or if a request for the specific entity's public information isacquired from the resolving server in response to the request for thespecific entity's DID document from the service providing server, theblockchain node performs or supports another device to perform (1) oneof (i) in response to the request for the specific entity's public keyfrom the service providing server, (i-1) a process of acquiring thespecific entity's public key corresponding to the specific entity's DIDfrom the blockchain network by referring to the specific entity's DID ora process of allowing the identity contract to acquire the specificentity's public key from the blockchain network by referring to thespecific entity's DID, and (i-2) a process of transmitting the specificentity's public key to the service providing server and (ii) in responseto the request for the specific entity's public information from theresolving server, (ii-1) a process of acquiring the specific entity'spublic information from the blockchain network by referring to thespecific entity's DID or a process of allowing the identity contract toacquire the specific entity's public information from the blockchainnetwork by referring to the specific entity's DID, and (ii-2) a processof allowing the resolving server to modify the specific entity's publicinformation into the specific entity's DID document and thus to transmitthe specific entity's DID document to the service providing server, andas a result, (2) a process of allowing the service providing server to(i) verify the specific entity's signature value by decrypting thespecific entity's signature value with the specific entity's public keyacquired from the blockchain node or from the specific entity's DIDdocument, and (ii) if the specific entity's signature value isdetermined as verified, broadcast the request for the relationalinformation to the blockchain network.

As one example, at the step of (a), the request for the registration ofthe relational information includes setting information and confirmationinformation, wherein another entity's device corresponding to saidanother entity's DID creates the setting information by setting arelation between the specific entity's DID and said another entity's DIDand wherein the specific entity's device creates the confirmationinformation by confirming the relation between the specific entity's DIDand said another entity's DID.

As one example, the setting information includes (1) the relationalinformation representing a relation between the specific entity's DIDand said another entity's DID, and (2) another entity's signature valuecreated by encrypting the relational information with another entity'sprivate key corresponding to said another entity's DID, and wherein theconfirmation information includes (1) the relational information and (2)a specific entity's signature value created by encrypting the relationalinformation with a specific entity's private key corresponding to thespecific entity's DID, and wherein the blockchain node performs orsupports another device to perform (i) (i-1) a process of acquiring aspecific entity's public key corresponding to the specific entity's DIDand another entity's public key corresponding to said another entity'sDID from the blockchain network by referring to the specific entity'sDID and said another entity's DID or (i-2) a process of allowing theidentity contract to acquire the specific entity's public key and saidanother entity's public key from the blockchain network by referring tothe specific entity's DID and said another entity's DID, (ii) a processof verifying the setting information by decrypting said another entity'ssignature value with said another entity's public key, and (iii) aprocess of verifying the confirmation information by decrypting thespecific entity's signature value with the specific entity's public key,to thereby verify the request for the registration of the relationalinformation.

As one example, if a request for said another entity's public key isacquired from the specific entity's device in response to the settinginformation transmitted from said another entity's device wherein saidanother entity's public key corresponds to said another entity's DID orif a request for another entity's public information is acquired from aresolving server in response to a request for another entity's DIDdocument from the specific entity's device wherein said another entity'spublic information is registered in the blockchain network ascorresponding to said another entity's DID and includes the relationalinformation and another entity's public key corresponding to saidanother entity's DID, the blockchain node performs or supports anotherdevice to perform (1) one of (i) in response to the request for saidanother entity's public key from the specific entity's device, (i-1) aprocess of acquiring said another entity's public key from theblockchain network by referring to said another entity's DID or aprocess of allowing the identity contract to acquire said anotherentity's public key from the blockchain network by referring to saidanother entity's DID, and (i-2) a process of transmitting said anotherentity's public key to the specific entity's device, and (ii) inresponse to the request for said another entity's public informationfrom the resolving server, (ii-1) a process of acquiring anotherentity's public information from the blockchain network by referring tosaid another entity's DID or a process of allowing the identity contractto acquire said another entity's public information from the blockchainnetwork by referring to said another entity's DID, and (ii-2) a processof allowing the resolving server to modify said another entity's publicinformation into said another entity's DID document and thus to transmitsaid another entity's DID document to the specific entity's device, andas a result, (2) a process of allowing the specific entity's device to(i) verify the setting information by decrypting said another entity'ssignature value with said another entity's public key acquired from theblockchain node or from said another entity's DID document, and (ii) ifthe setting information is determined as verified, broadcast the requestfor the registration of the relational information to the blockchainnetwork.

As one example, if the setting information broadcast from said anotherentity's device to the blockchain network is acquired, the blockchainnode performs or supports another device to perform a process oftransmitting the setting information to the specific entity's device ora process of allowing the identity contract to transmit the settinginformation to the specific entity's device, to thereby allow thespecific entity's device to broadcast the request for the registrationof the relational information to the blockchain network in response to averification result on the setting information which is verified by thespecific entity's device and thus acquire the request for theregistration of the relational information.

As one example, if the setting information is broadcast from saidanother entity's device to the blockchain network, the blockchain nodeperforms or supports another device to perform (i) a process ofacquiring another entity's public key from the blockchain network byreferring to said another entity's DID or a process of allowing theidentity contract to acquire said another entity's public key from theblockchain network by referring to said another entity's DID, (ii) aprocess of verifying the setting information by decrypting said anotherentity's signature value with said another entity's public key, and(iii) if the setting information is determined as verified, a process oftransmitting the setting information to the specific entity's device ora process of allowing the identity contract to transmit a verificationresult on the setting information to said another entity's device andthus to allow said another entity's device to transmit the settinginformation to the specific entity's device, and wherein, if theconfirmation information is broadcast from the specific entity's deviceto the blockchain network, the blockchain node performs or supportsanother device to perform (i) a process of acquiring a specific entity'spublic key from the blockchain network by referring to the specificentity's DID, or a process of allowing the identity contract to acquirethe specific entity's public key from the blockchain network byreferring to the specific entity's DID, and (ii) a process of verifyingthe confirmation information by decrypting the specific entity'ssignature value with the specific entity's public key.

In accordance with another aspect of the present disclosure, there isprovided a blockchain node for providing a relational DID (decentralizedidentifier) service, including: at least one memory that storesinstructions; and at least one processor configured to execute theinstructions to perform or support another device to perform: (I) if arequest for registration of relational information is broadcast from aspecific entity's device to a blockchain network, wherein the relationalinformation represents information on a relation between a specificentity's DID of a specific entity and another entity's DID of anotherentity and wherein the relational information is set by said anotherentity and confirmed by the specific entity, one of (i) a process ofverifying the request for the registration of the relational informationand (ii) a process of transmitting the request for the registration ofthe relational information to an identity contract registered in theblockchain network, to thereby allow the identity contract to verify therequest for the registration of the relational information, and (II) oneof (i) a process of registering the relational information in theblockchain network as corresponding to the specific entity's DID andsaid another entity's DID if the request for the registration of therelational information is determined as verified by the blockchain node,and (ii) a process of allowing the identity contract to register therelational information in the blockchain network as corresponding to thespecific entity's DID and said another entity's DID if the request forthe registration of the relational information is determined as verifiedby the identity contract.

As one example, the processor further performs or supports anotherdevice to perform: (III) if a request for the relational information isacquired from a service providing server in response to a request for aservice transmitted from the specific entity's device wherein theservice is accessible with said another entity's DID or if a request forDID public information is acquired from a resolving server in responseto a request for a DID document from the service providing server,wherein the request for the DID document is at least one of a requestfor a specific entity's DID document and a request for another entity'sDID document, wherein the DID public information includes at least oneof specific entity's public information and another entity's publicinformation, wherein the specific entity's public information isregistered in the blockchain network as corresponding to the specificentity's DID and includes the relational information and a specificentity's public key corresponding to the specific entity's DID, andwherein said another entity's public information is registered in theblockchain network as corresponding to said another entity's DID andincludes the relational information and another entity's public keycorresponding to said another entity's DID, (1) one of (i) in responseto the request for the relational information from the service providingserver, (i-1) a process of acquiring the relational information from theblockchain network by referring to the specific entity's DID or saidanother entity's DID or a process of allowing the identity contract toacquire the relational information from the blockchain network byreferring to the specific entity's DID or said another entity's DID, and(i-2) a process of transmitting the relational information to theservice providing server, and (ii) in response to the request for theDID public information from the resolving server, (ii-1) a process ofacquiring the DID public information from the blockchain network byreferring to at least one of the specific entity's DID and said anotherentity's DID or a process of allowing the identity contract to acquirethe DID public information from the blockchain network by referring toat least one of the specific entity's DID and said another entity's DID,and (ii-2) a process of allowing the resolving server to modify the DIDpublic information into the DID document and thus to transmit the DIDdocument to the service providing server, and as a result, (2) a processof allowing the service providing server to (i) confirm a relationbetween the specific entity's DID and said another entity's DID byreferring to one of the relational information acquired from theblockchain node and the relational information acquired from the DIDdocument, and (ii) if the relation between the specific entity's DID andsaid another entity's DID is confirmed by using the relationalinformation, provide the service corresponding to said another entity'sDID to the specific entity's device.

As one example, the request for the service transmitted from thespecific entity's device includes a specific entity's signature valuecreated by encrypting the request for the service with a specificentity's private key corresponding to the specific entity's DID, andwherein, if a request for the specific entity's public key correspondingto the specific entity's DID is acquired from the service providingserver or if a request for the specific entity's public information isacquired from the resolving server in response to the request for thespecific entity's DID document from the service providing server, theprocessor performs or supports another device to perform (1) one of (i)in response to the request for the specific entity's public key from theservice providing server, (i-1) a process of acquiring the specificentity's public key corresponding to the specific entity's DID from theblockchain network by referring to the specific entity's DID or aprocess of allowing the identity contract to acquire the specificentity's public key from the blockchain network by referring to thespecific entity's DID, and (i-2) a process of transmitting the specificentity's public key to the service providing server and (ii) in responseto the request for the specific entity's public information from theresolving server, (ii-1) a process of acquiring the specific entity'spublic information from the blockchain network by referring to thespecific entity's DID or a process of allowing the identity contract toacquire the specific entity's public information from the blockchainnetwork by referring to the specific entity's DID, and (ii-2) a processof allowing the resolving server to modify the specific entity's publicinformation into the specific entity's DID document and thus to transmitthe specific entity's DID document to the service providing server, andas a result, (2) a process of allowing the service providing server to(i) verify the specific entity's signature value by decrypting thespecific entity's signature value with the specific entity's public keyacquired from the blockchain node or from the specific entity's DIDdocument, and (ii) if the specific entity's signature value isdetermined as verified, broadcast the request for the relationalinformation to the blockchain network.

As one example, at the process of (I), the request for the registrationof the relational information includes setting information andconfirmation information, wherein another entity's device correspondingto said another entity's DID creates the setting information by settinga relation between the specific entity's DID and said another entity'sDID and wherein the specific entity's device creates the confirmationinformation by confirming the relation between the specific entity's DIDand said another entity's DID.

As one example, the setting information includes (1) the relationalinformation representing a relation between the specific entity's DIDand said another entity's DID, and (2) another entity's signature valuecreated by encrypting the relational information with another entity'sprivate key corresponding to said another entity's DID, and wherein theconfirmation information includes (1) the relational information and (2)a specific entity's signature value created by encrypting the relationalinformation with a specific entity's private key corresponding to thespecific entity's DID, and wherein the processor performs or supportsanother device to perform (i) (i-1) a process of acquiring a specificentity's public key corresponding to the specific entity's DID andanother entity's public key corresponding to said another entity's DIDfrom the blockchain network by referring to the specific entity's DIDand said another entity's DID or (i-2) a process of allowing theidentity contract to acquire the specific entity's public key and saidanother entity's public key from the blockchain network by referring tothe specific entity's DID and said another entity's DID, (ii) a processof verifying the setting information by decrypting said another entity'ssignature value with said another entity's public key, and (iii) aprocess of verifying the confirmation information by decrypting thespecific entity's signature value with the specific entity's public key,to thereby verify the request for the registration of the relationalinformation.

As one example, if a request for said another entity's public key isacquired from the specific entity's device in response to the settinginformation transmitted from said another entity's device wherein saidanother entity's public key corresponds to said another entity's DID orif a request for another entity's public information is acquired from aresolving server in response to a request for another entity's DIDdocument from the specific entity's device wherein said another entity'spublic information is registered in the blockchain network ascorresponding to said another entity's DID and includes the relationalinformation and another entity's public key corresponding to saidanother entity's DID, the processor performs or supports another deviceto perform (1) one of (i) in response to the request for said anotherentity's public key from the specific entity's device, (i-1) a processof acquiring said another entity's public key from the blockchainnetwork by referring to said another entity's DID or a process ofallowing the identity contract to acquire said another entity's publickey from the blockchain network by referring to said another entity'sDID, and (i-2) a process of transmitting said another entity's publickey to the specific entity's device, and (ii) in response to the requestfor said another entity's public information from the resolving server,(ii-1) a process of acquiring another entity's public information fromthe blockchain network by referring to said another entity's DID or aprocess of allowing the identity contract to acquire said anotherentity's public information from the blockchain network by referring tosaid another entity's DID, and (ii-2) a process of allowing theresolving server to modify said another entity's public information intosaid another entity's DID document and thus to transmit said anotherentity's DID document to the specific entity's device, and as a result,(2) a process of allowing the specific entity's device to (i) verify thesetting information by decrypting said another entity's signature valuewith said another entity's public key acquired from the blockchain nodeor from said another entity's DID document, and (ii) if the settinginformation is determined as verified, broadcast the request for theregistration of the relational information to the blockchain network.

As one example, if the setting information broadcast from said anotherentity's device to the blockchain network is acquired, the processorperforms or supports another device to perform a process of transmittingthe setting information to the specific entity's device or a process ofallowing the identity contract to transmit the setting information tothe specific entity's device, to thereby allow the specific entity'sdevice to broadcast the request for the registration of the relationalinformation to the blockchain network in response to a verificationresult on the setting information which is verified by the specificentity's device and thus acquire the request for the registration of therelational information.

As one example, if the setting information is broadcast from saidanother entity's device to the blockchain network, the processorperforms or supports another device to perform (i) a process ofacquiring another entity's public key from the blockchain network byreferring to said another entity's DID or a process of allowing theidentity contract to acquire said another entity's public key from theblockchain network by referring to said another entity's DID, (ii) aprocess of verifying the setting information by decrypting said anotherentity's signature value with said another entity's public key, and(iii) if the setting information is determined as verified, a process oftransmitting the setting information to the specific entity's device ora process of allowing the identity contract to transmit a verificationresult on the setting information to said another entity's device andthus to allow said another entity's device to transmit the settinginformation to the specific entity's device, and wherein, if theconfirmation information is broadcast from the specific entity's deviceto the blockchain network, the processor performs or supports anotherdevice to perform (i) a process of acquiring a specific entity's publickey from the blockchain network by referring to the specific entity'sDID, or a process of allowing the identity contract to acquire thespecific entity's public key from the blockchain network by referring tothe specific entity's DID, and (ii) a process of verifying theconfirmation information by decrypting the specific entity's signaturevalue with the specific entity's public key.

In addition, recordable media that are readable by a computer forstoring a computer program to execute the method of the presentdisclosure is further provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present disclosure willbecome apparent from the following description of preferred embodimentsgiven in conjunction with the accompanying drawings, in which:

FIG. 1 is a drawing schematically illustrating a system for providing arelational decentralized identifier service in accordance with oneexample embodiment of the present disclosure.

FIG. 2 is a drawing schematically illustrating a method for providingthe relational decentralized identifier service in accordance with oneexample embodiment of the present disclosure.

FIG. 3 is a drawing schematically illustrating a method for providingthe relational decentralized identifier service in accordance withanother example embodiment of the present disclosure.

FIG. 4 is a drawing schematically illustrating a method for providingthe relational decentralized identifier service in accordance with stillanother example embodiment of the present disclosure.

FIG. 5 is a drawing schematically illustrating a method for providingthe relational decentralized identifier service in accordance with stillyet another example embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings that show, by way of illustration, specificembodiments in which the present disclosure may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the present disclosure. It is to be understoodthat the various embodiments of the present disclosure, althoughdifferent, are not necessarily mutually exclusive. For example, aparticular feature, structure, or characteristic described herein inconnection with one embodiment may be implemented within otherembodiments without departing from the spirit and scope of the presentdisclosure. In addition, it is to be understood that the position orarrangement of individual elements within each disclosed embodiment maybe modified without departing from the spirit and scope of the presentdisclosure. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope of the present disclosure isdefined only by the appended claims, appropriately interpreted, alongwith the full range of equivalents to which the claims are entitled. Inthe drawings, like numerals refer to the same or similar functionalitythroughout the several views.

The headings and abstract of the present disclosure provided herein arefor convenience only and do not limit or interpret the scope or meaningof the embodiments.

To allow those skilled in the art to the present disclosure to becarried out easily, the example embodiments of the present disclosure byreferring to attached diagrams will be explained in detail as shownbelow.

FIG. 1 is a drawing schematically illustrating a system for providing arelational decentralized identifier service in accordance with oneexample embodiment of the present disclosure. The system may includeentity's devices 100, a blockchain network 200, a service providingserver 300, and a resolving server 400.

First, each of the entity's devices 100 may correspond to each ofentities who/which has intention to use the relational decentralizedidentifier service, and may store (1) its issued DID (decentralizedidentifier) and (2) its PI (personal identity) or a VC (verifiablecredential). Herein, the personal identity may correspond to the DID,and a certificate authority may create the VC by authenticating thepersonal identity. Herein, the entities may include users, IoT (Internetof things) devices, etc., but the scope of the present disclosure is notlimited thereto, and may include any object which can be identified by aDID.

Next, multiple blockchain nodes in the blockchain network 200 may sharedistributed ledgers. The blockchain network 200 may generate blocks by adistributed consensus and store the generated blocks, in a form ofchain, in the distributed ledgers, may generate the DIDs in response torequests from the users and/or the computing devices, and may store thedata corresponding to the DIDs in the distributed ledgers. And, theblockchain network 200 may allow a registered identity contract toprocess data related to the DIDs.

Also, in response to a request for registration of relationalinformation among the entity's devices 100, the blockchain network 200may register the relational information among the entities and provide arelational DID service.

Herein, the blockchain network 200 may be comprised of the multipleblockchain nodes, and each of the multiple blockchain nodes 210 mayinclude a memory (not illustrated) for storing instructions to providethe relational DID service, and a processor (not illustrated) forperforming processes of providing the relational DID service, accordingto the instructions stored in the memory. And, the blockchain node 210may include a mobile computer, a PDA/EDA (personal/enterprise digitalassistant), a mobile phone, a smart-phone, a tablet, and a server, butthe scope of the present disclosure is not limited thereto, and mayinclude any computing device which performs computational operation,such as a digital camera, a personal navigation device, and a mobilegaming device capable of wired and wireless communication, etc.

Specifically, the blockchain node 210 may typically achieve a desiredsystem performance by using combinations of at least one computingdevice and at least one computer software, e.g., a computer processor, amemory, a storage, an input device, an output device, or any otherconventional computing components, an electronic communication devicesuch as a router or a switch, an electronic information storage systemsuch as a network-attached storage (NAS) device and a storage areanetwork (SAN) as the computing device and any instructions that allowthe computing device to function in a specific way as the computersoftware.

The communication part of such devices may transmit requests to andreceive responses from other linked devices. As one example, suchrequests and responses may be carried out by the same TCP (transmissioncontrol protocol) session, but the scope of the present disclosure isnot limited thereto. For example, they could be transmitted and receivedas UDP (user datagram protocol) datagrams.

Also, the processors of such devices may include hardware configurationof MPU (Micro Processing Unit) or CPU (Central Processing Unit), cachememory, data bus, etc. Additionally, any OS (operating system) andsoftware configuration of applications that achieve specific purposesmay be further included.

Next, the service providing server 300 may provide a service requestedfrom each of the entity's devices 100.

Then, the resolving server 400 may acquire the data, i.e., publicinformation, which are registered in the blockchain network ascorresponding to the DIDs. Herein, the resolving server 400 may be thecomputing device capable of accessing a network or may be a blockchainnode in the blockchain network.

A method for providing the relational DID service using the systemconfigured as such in accordance with one example embodiment of thepresent disclosure is described as follows by referring to FIG. 2.

First, a specific entity and another entity may respectively register aspecific entity's DID and another entity's DID in the blockchain network200 by respectively using a specific entity's device 110 and anotherentity's device 120. And, the blockchain network 200 may store (i) aspecific entity's public key, a specific entity's virtual asset address,etc. which are specific entity's public information corresponding to thespecific entity's DID, and (ii) another entity's public key, anotherentity's virtual asset address, etc. which are another entity's publicinformation corresponding to said another entity's DID. Herein, theblockchain network 200 may allow the registered identity contract toperform operation related to the DIDs. And, the identity contract may bea smart contract which performs the operation related to the DIDs, maybe configured as operation code for performing the operation related tothe DIDs, and may be executed on the blockchain network. Also, theidentity contract may include the operation code to be used forinteraction with other smart contracts which utilize the DIDs. And if anentity requests other services accessible with the DIDs, the identitycontract may allow the entity to use said other services through theinteraction with said other smart contracts.

Thereafter, in order to set a relation between the specific entity andsaid another entity through said another entity's device 120, saidanother entity may transmit setting information to the specific entity'sdevice 110 at a step of S1. Herein, the setting information mayrepresent required information to be used for setting the relationbetween the specific entity and said another entity.

Also, the setting information may include (1) the relational informationrepresenting the relation between the specific entity's DID and saidanother entity's DID, respectively corresponding to the specific entityand said another entity, and (2) another entity's signature valuecreated by encrypting the relational information with another entity'sprivate key corresponding to said another entity's DID. And therelational information may include information on relations amongvarious entities, for example, an IoT device and its owner, a parent andhis/her child, an employee and his/her employer, a student and his/herprofessor, etc. As used in this specification and the appended claims,the singular forms “a,” “an,” and “the” include plural referents, i.e.,one or more, unless the content and context clearly dictates otherwise.As one example, the relational information may be set as representingthat “the specific entity's DID is the owner of said another entity'sDID”.

Then, the specific entity's device 110 may verify the settinginformation transmitted from said another entity's device 120, at a stepof S4.

As one example, in order to acquire said another entity's public keycorresponding to said another entity's DID, the specific entity's device110 may broadcast a request for said another entity's public key to theblockchain network 200 at a step of S2. Then, in response to the requestfor said another entity's public key, at least one blockchain node 210in the blockchain network 200 may perform or support another device toperform (i) a process of acquiring said another entity's public keycorresponding to said another entity's DID from the blockchain network200, and (ii) a process of transmitting said another entity's publickey, acquired from the blockchain network 200, to the specific entity'sdevice 110 at a step of S3. As another example, the blockchain node 210may perform or support another device to perform (i) a process ofallowing the identity contract registered in the blockchain network 200to acquire said another entity's public key from the blockchain network200 by referring to said another entity's DID, and (ii) a process oftransmitting said another entity's public key to the specific entity'sdevice 110 at the step of S3. And, the specific entity's device 110 mayverify the setting information by decrypting another entity's signaturevalue with said another entity's public key transmitted from theblockchain node 210, at a step of S4. Herein, the setting informationmay be verified by determining whether the relational informationacquired by decrypting said another entity's signature value isidentical to the relational information included in the settinginformation.

Thereafter, if the setting information is determined as verified, thespecific entity's device 110 may broadcast the request for theregistration of the relational information to the blockchain network 200at a step of S5.

Herein, the request for the registration of the relational informationmay include (1) the setting information transmitted from said anotherentity's device 120 and (2) confirmation information which is created atthe specific entity's device 110 by confirming the relation between thespecific entity's DID and said another entity's DID. And, theconfirmation information may include (1) the relational information and(2) a specific entity's signature value created by encrypting therelational information with a specific entity's private keycorresponding to the specific entity's DID.

And, the blockchain node 210 may perform or support another device toperform a process of receiving the request for the registration of therelational information and a process of verifying the request for theregistration of the relational information at a step of S6. Herein, theregistration of the relational information has been broadcast to theblockchain network 200 from the specific entity's device 110.

As one example, the blockchain node 210 may perform or support anotherdevice to perform a process of acquiring the specific entity's publickey and said another entity's public key from the blockchain network 200by referring to the specific entity's DID and said another entity's DID.As another example, the blockchain node 210 may perform or supportanother device to perform a process of allowing the identity contract toacquire the specific entity's public key and said another entity'spublic key from the blockchain network 200 by referring to the specificentity's DID and said another entity's DID. And, the blockchain node 210may perform or support another device to perform (i) a process ofverifying the setting information by decrypting said another entity'ssignature value, included in the setting information, with said anotherentity's public key, and (ii) a process of verifying the confirmationinformation by decrypting the specific entity's signature value,included in the confirmation information, with the specific entity'spublic key, to thereby verify the request for the registration of therelational information. Herein, the setting information may be verifiedby determining whether the relational information acquired by decryptingsaid another entity's signature value is identical to the relationalinformation included in the setting information. And the confirmationinformation may be verified by determining whether the relationalinformation acquired by decrypting the specific entity's signature valueis identical to the relational information included in the confirmationinformation.

Meanwhile, as another example different from verifying the request forthe registration of the relational information by the blockchain node210 itself, the blockchain node 210 may perform or support anotherdevice to perform a process of transmitting the request for theregistration of the relational information to the identity contract, tothereby allow the identity contract to verify the request for theregistration of the relational information.

Thereafter, the blockchain node 210 may perform or support anotherdevice to perform one of (i) a process of registering the relationalinformation in the blockchain network 200 as corresponding to thespecific entity's DID and said another entity's DID if the request forthe registration of the relational information is determined as verifiedby the blockchain node, at a step of S7, and (ii) a process of allowingthe identity contract to register the relational information in theblockchain network 200 as corresponding to the specific entity's DID andsaid another entity's DID if the request for the registration of therelational information is determined as verified by the identitycontract, at the step of S7.

Meanwhile, said another entity's device 120 is shown above astransmitting the setting information to the specific entity's device110, but as another example, the setting information may be transmittedto the specific entity's device 110 by the blockchain network 200.

That is, if said another entity's device 120 broadcasts the settinginformation to the blockchain network 200, the blockchain node 210 mayreceive the setting information and then may transmit or allow theidentity contract to transmit the setting information to the specificentity's device 110. And, if the specific entity's device 110 broadcaststhe request for the registration of the relational information to theblockchain network 200 where the request for the registration of therelational information includes the setting information and theconfirmation information, then the blockchain node 210 may acquire therequest for the registration of the relational information which hasbeen broadcast to the blockchain network 200.

On condition that the relational information on a relation between thespecific entity's DID and said another entity's DID have been registeredin the blockchain network 200 as above, in order to provide the specificentity with a service which is accessible with said another entity'sDID, a request for the service may be transmitted to the serviceproviding server 300 by using the specific entity's device 110 at a stepof S8. Herein, the request for the service may include the specificentity's signature value created by encrypting the request for theservice with the specific entity's private key corresponding to thespecific entity's DID.

Then, the service providing server 300 may verify the request for theservice, where the service is accessible with said another entity's DID,transmitted from the specific entity's device 110, at a step of S11.

As one example, the service providing server 300 may broadcast a requestfor the specific entity's public key, corresponding to the specificentity's DID, to the blockchain network 200 at a step of S9. Then, theblockchain node 210 may perform or support another device to perform (i)a process of acquiring the request for the specific entity's public keybroadcast to the blockchain network 200, (ii) a process of acquiring thespecific entity's public key, corresponding to the specific entity'sDID, from the blockchain network 200 in response to the request for thespecific entity's public key, and (iii) a process of transmitting thespecific entity's public key, acquired from the blockchain network 200,to the service providing server 300 at a step of S10. As anotherexample, the blockchain node 210 may perform or support another deviceto perform (i) a process of allowing the identity contract registered inthe blockchain network 200 to acquire the specific entity's public keyfrom the blockchain network 200 by referring to the specific entity'sDID, and (ii) a process of transmitting the specific entity's public keyto the service providing server 300 at the step of S10. And, the serviceproviding server 300 may verify the request for the service bydecrypting the specific entity's signature value, which is included inthe request for the service, with the specific entity's public keytransmitted from the blockchain node 210, at a step of S11. Herein, therequest for the service may be verified by determining whether therequest for the service acquired by decrypting the specific entity'ssignature value is identical to the request for the service transmittedfrom the specific entity's device 110.

Thereafter, if the request for the service is determined as verified,the service providing server 300 may broadcast a request for therelational information to the blockchain network 200 at a step of S12.

Herein, the request for the relational information may include thespecific entity's DID or said another entity's DID.

And, the blockchain node 210 may perform or support another device toperform (i) a process of receiving the request for the relationalinformation broadcast to the blockchain network 200, (ii) in response tothe request for the relational information, one of (ii-1) a process ofacquiring the relational information from the blockchain network 200 byreferring to the specific entity's DID or said another entity's DID and(ii-2) a process of allowing the identity contract to acquire therelational information from the blockchain network 200 by referring tothe specific entity's DID or said another entity's DID, and (iii) aprocess of transmitting the relational information to the serviceproviding server 300 at a step of S13.

And, the service providing server 300 may confirm the relation betweenthe specific entity's DID and said another entity's DID by referring tothe relational information acquired from the blockchain node 210, at astep of S14.

Thereafter, if the relation between the specific entity's DID and saidanother entity's DID is confirmed by referring to the relationalinformation, then the service accessible with said another entity's DIDmay be provided to the specific entity's device 110 at a step of S15. Asone example, if the relational information represents that “the specificentity's DID is the owner of said another entity's DID”, and if therequest for the service represents a log-on request using said anotherentity's DID, the service providing server 300 may confirm that thespecific entity's DID is the owner of said another entity's DID byreferring to the relational information, and may allow the specificentity's device 110 to log-on by using said another entity's DID.

FIG. 3 is a drawing schematically illustrating a method for providingthe relational DID service in accordance with another example embodimentof the present disclosure. The method for providing the relational DIDservice in accordance with another example embodiment of the presentdisclosure is described by referring to FIG. 3 as follows.

In order to set the relation with the specific entity, said anotherentity may transmit the setting information to the specific entity'sdevice 110 at a step of S21. Herein, the setting information mayrepresent the relation between the specific entity and said anotherentity, where the relation may be set by using said another entity'sdevice 120.

Herein, the setting information may include (1) the relationalinformation representing the relation between the specific entity's DIDand said another entity's DID, respectively corresponding to thespecific entity and said another entity, and (2) said another entity'ssignature value created by encrypting the relational information withsaid another entity's private key corresponding to said another entity'sDID. And the relational information may include information on relationsamong various entities, such as an IoT device and its owner, a parentand his/her child, an employee and his/her employer, a student andhis/her professor, etc. As one example, the relational information maybe set as representing that “the specific entity's DID is the owner ofsaid another entity's DID”.

Then, the specific entity's device 110 may verify the settinginformation transmitted from said another entity's device 120, at a stepof S26.

As one example, in order to acquire said another entity's public keycorresponding to said another entity's DID, the specific entity's device110 may transmit a request for another entity's DID document,corresponding to said another entity's DID, to the resolving server 400,at a step of S22. And, in response to the request for said anotherentity's DID document from the specific entity's device 110, theresolving server 400 may broadcast a request for said another entity'spublic information to the blockchain network 200 at a step of S23.Herein, said another entity's public information may be registered inthe blockchain network 200 as corresponding to said another entity's DIDand may include the relational information and another entity's publickey corresponding to said another entity's DID. Then, in response to therequest for said another entity's public information, at least oneblockchain node 210 in the blockchain network 200 may perform or supportanother device to perform (i) a process of acquiring said anotherentity's public information corresponding to said another entity's DIDfrom the blockchain network 200, and (ii) a process of transmitting saidanother entity's public information, acquired from the blockchainnetwork 200, to the resolving server 400 at a step of S24. As anotherexample, the blockchain node 210 may perform or support another deviceto perform (i) a process of allowing the identity contract registered inthe blockchain network 200 to acquire said another entity's publicinformation from the blockchain network 200 by referring to said anotherentity's DID, and (ii) a process of transmitting said another entity'spublic information to the resolving server 400. And, the resolvingserver 400 may modify said another entity's public information,transmitted from the blockchain node 210, into said another entity's DIDdocument, and may transmit said another entity's DID document to thespecific entity's device 110 at a step of S25. Then, the specificentity's device 110 may acquire said another entity's public key fromsaid another entity's DID document which is transmitted from theresolving server 400, and may verify the setting information bydecrypting said another entity's signature value with said anotherentity's public key, at the step of S26. Herein, the setting informationmay be verified by determining whether the relational informationacquired by decrypting said another entity's signature value isidentical to the relational information included in the settinginformation.

Thereafter, if the setting information is determined as verified, thespecific entity's device 110 may broadcast the request for theregistration of the relational information to the blockchain network 200at a step of S27.

Herein, the request for the registration of the relational informationmay include (1) the setting information transmitted from said anotherentity's device 120 and (2) the confirmation information where thespecific entity's device 110 may create the confirmation information byconfirming the relational information between the specific entity's DIDand said another entity's DID. And, the confirmation information mayinclude (1) the relational information and (2) the specific entity'ssignature value created by encrypting the relational information withthe specific entity's private key corresponding to the specific entity'sDID.

And, the blockchain node 210 may perform or support another device toperform a process of receiving the request for the registration of therelational information where the request is broadcast to the blockchainnetwork 200 by the specific entity's device 110, and a process ofverifying the request for the registration of the relational informationat a step of S28.

As one example, the blockchain node 210 may perform or support anotherdevice to perform a process of acquiring the specific entity's publickey and said another entity's public key from the blockchain network 200by referring to the specific entity's DID and said another entity's DID.As another example, the blockchain node 210 may perform or supportanother device to perform a process of allowing the identity contract toacquire the specific entity's public key and said another entity'spublic key from the blockchain network 200 by referring to the specificentity's DID and said another entity's DID. And, the blockchain node 210may perform or support another device to perform a process of verifyingthe setting information by decrypting said another entity's signaturevalue, included in the setting information, with said another entity'spublic key, and a process of verifying the confirmation information bydecrypting the specific entity's signature value, included in theconfirmation information, with the specific entity's public key, tothereby verify the request for the registration of the relationalinformation. Herein, the setting information may be verified bydetermining whether the relational information acquired by decryptingsaid another entity's signature value is identical to the relationalinformation included in the setting information. And the confirmationinformation may be verified by determining whether the relationalinformation acquired by decrypting the specific entity's signature valueis identical to the relational information included in the confirmationinformation.

Meanwhile, as another example different from verifying the request forthe registration of the relational information by the blockchain node210 itself, the blockchain node 210 may perform or support anotherdevice to perform a process of transmitting the request for theregistration of the relational information to the identity contract, tothereby allow the identity contract to verify the request for theregistration of the relational information.

Thereafter, the blockchain node 210 may perform or support anotherdevice to perform one of (i) a process of registering the relationalinformation in the blockchain network 200 as corresponding to thespecific entity's DID and said another entity's DID if the request forthe registration of the relational information is determined as verifiedby the blockchain node, at a step of S29, and (ii) a process of allowingthe identity contract to register the relational information in theblockchain network 200 as corresponding to the specific entity's DID andsaid another entity's DID if the request for the registration of therelational information is determined as verified by the identitycontract, at the step of S29.

Meanwhile, said another entity's device 120 is shown above astransmitting the setting information to the specific entity's device110, but as another example, the setting information may be transmittedto the specific entity's device 110 by the blockchain network 200.

That is, if said another entity's device 120 broadcasts the settinginformation to the blockchain network 200, the blockchain node 210 mayreceive the setting information broadcast to the blockchain network 200,and may transmit or allow the identity contract to transmit the settinginformation to the specific entity's device 110.

On condition that the relational information on a relation between thespecific entity's DID and said another entity's DID have been registeredin the blockchain network 200 as above, in order to provide the specificentity with the service which is accessible with said another entity'sDID, the request for the service may be transmitted to the serviceproviding server 300 by using the specific entity's device 110 at a stepof S30. Herein, the request for the service may include the specificentity's signature value created by encrypting the request for theservice with the specific entity's private key corresponding to thespecific entity's DID.

Then, the service providing server 300 may verify the request for theservice, where the service is accessible with said another entity's DID,transmitted from the specific entity's device 110, at a step of S35.

As one example, in order to acquire the specific entity's public keycorresponding to the specific entity's DID, the specific entity's device300 may transmit the request for the specific entity's DID document,corresponding to the specific entity's DID, to the resolving server 400,at a step of S31. And, in response to the request for the specificentity's DID document from the service providing server 300, theresolving server 400 may broadcast the request for the specific entity'spublic information to the blockchain network 200 at a step of S32.Herein, the specific entity's public information may be registered inthe blockchain network 200 as corresponding to the specific entity's DIDand may include the relational information and the specific entity'spublic key corresponding to the specific entity's DID. Then, in responseto the request for the specific entity's public information, at leastone blockchain node 210 in the blockchain network 200 may perform orsupport another device to perform (i) a process of acquiring thespecific entity's public information, corresponding to the specificentity's DID, from the blockchain network 200, and (ii) a process oftransmitting the specific entity's public information, acquired from theblockchain network 200, to the resolving server 400 at a step of S33. Asanother example, the blockchain node 210 may perform or support anotherdevice to perform (i) a process of allowing the identity contractregistered in the blockchain network 200 to acquire the specificentity's public information from the blockchain network 200 by referringto the specific entity's DID, and (ii) a process of transmitting thespecific entity's public information to the resolving server 400. And,the resolving server 400 may modify the specific entity's publicinformation, transmitted from the blockchain node 210, into the specificentity's DID document, and may transmit the specific entity's DIDdocument to the service providing server 300 at a step of S34. And, theservice providing server 300 may acquire the specific entity's publickey from the specific entity's DID document which is transmitted fromthe resolving server 400, and may verify the request for the service bydecrypting the specific entity's signature value, which is included inthe request for the service, with the specific entity's public key, at astep of S35. Herein, the request for the service may be verified bydetermining whether the request for the service acquired by decryptingthe specific entity's signature value is identical to the request forthe service transmitted from the specific entity's device 110.

Thereafter, if the request for the service is determined as verified,the service providing server 300 may transmit the request for the DIDdocument to the resolving server 400 at a step of S36.

Herein, the request for the DID document may be at least one of therequest for the specific entity's DID document and the request for saidanother entity's DID document.

Then, in response to the request for the DID document from the serviceproviding server 300, the resolving server 400 may broadcast the requestfor the DID public information, corresponding to the request for the DIDdocument, to the blockchain network 200 at a step of S37.

Herein, the DID public information may include at least one of thespecific entity's public information and said another entity's publicinformation. And, the specific entity's public information may beregistered in the blockchain network 200 as corresponding to thespecific entity's DID and may include the relational information and thespecific entity's public key corresponding to the specific entity's DID.Also, said another entity's public information may be registered in theblockchain network 200 as corresponding to said another entity's DID andmay include the relational information and another entity's public keycorresponding to said another entity's DID.

And, the blockchain node 210 may perform or support another device toperform (i) a process of receiving the request for the DID publicinformation broadcast to the blockchain network 200, (ii) in response tothe request for the DID public information, one of (ii-1) a process ofacquiring the DID public information from the blockchain network 200 byreferring to at least one of the specific entity's DID and said anotherentity's DID, and (ii-2) a process of allowing the identity contract toacquire the DID public information from the blockchain network 200 byreferring to at least one of the specific entity's DID and said anotherentity's DID, and (iii) a process of transmitting the DID publicinformation to the resolving server 400 at a step of S38.

Then, the resolving server 400 may modify the DID public informationinto the DID document, and may transmit the DID document to the serviceproviding server 300 at a step of S39.

And, the service providing server 300 may confirm the relation betweenthe specific entity's DID and said another entity's DID by referring tothe relational information acquired from the DID document, at a step ofS40.

Thereafter, if the relation between the specific entity's DID and saidanother entity's DID is confirmed by referring to the relationalinformation, the service accessible with said another entity's DID maybe provided to the specific entity's device 110 at a step of S41. As oneexample, if the relational information represents that “the specificentity's DID is the owner of said another entity's DID”, and if therequest for the service represents a log-on request using said anotherentity's DID, the service providing server 300 may confirm that thespecific entity's DID is the owner of said another entity's DID byreferring to the relational information, and may allow the specificentity's device 110 to log-on by using said another entity's DID.

FIG. 4 is a drawing schematically illustrating a method for providingthe relational DID service in accordance with still another exampleembodiment of the present disclosure. The method for providing therelational DID service in accordance with still another exampleembodiment of the present disclosure is described by referring to FIG. 4as follows. In the description below, the part easily deducible from theexplanation of FIGS. 2 and 3 will be omitted.

In order to set the relation with the specific entity, said anotherentity may broadcast the setting information to the blockchain network200 at a step of S51. Herein, the setting information may represent therelation between the specific entity and said another entity, where therelation may be set by using said another entity's device 120.

Herein, the setting information may include (1) the relationalinformation representing the relation between the specific entity's DIDand said another entity's DID, respectively corresponding to thespecific entity and said another entity, and (2) said another entity'ssignature value created by encrypting the relational information withsaid another entity's private key corresponding to said another entity'sDID. And the relational information may include information on relationsamong various entities, such as an IoT device and its owner, a parentand his/her child, an employee and his/her employer, a student andhis/her professor, etc. As one example, the relational information maybe set as representing that “the specific entity's DID is the owner ofsaid another entity's DID”.

Then, at least one blockchain node 210 in the blockchain network 200 mayreceive the setting information broadcast to the blockchain network 200,and may verify the received setting information at a step of S52.

As one example, the blockchain node 210 may perform or support anotherdevice to perform a process of acquiring said another entity's publickey from the blockchain network 200 by referring to said anotherentity's DID. As another example, the blockchain node 210 may perform orsupport another device to perform a process of allowing the identitycontract to acquire said another entity's public key from the blockchainnetwork 200 by referring to said another entity's DID. And, theblockchain node 210 may perform or support another device to perform aprocess of verifying the setting information by decrypting said anotherentity's signature value, included in the setting information, with saidanother entity's public key. Herein, the setting information may beverified by determining whether the relational information acquired bydecrypting said another entity's signature value is identical to therelational information included in the setting information. Meanwhile,as another example different from verifying the setting information bythe blockchain node 210 itself, the blockchain node 210 may perform orsupport another device to perform a process of transmitting the settinginformation to the identity contract, to thereby allow the identitycontract to verify the setting information.

Thereafter, if the setting information is determined as verified, theblockchain node 210 may perform or support another device to perform aprocess of transmitting the setting information, acquired from saidanother entity's device 120, to the specific entity's device 110 at astep of S53. Also, the blockchain node 210 may allow the identitycontract to transmit a verification result on the setting information tosaid another entity's device 120, to thereby allow said another entity'sdevice 120 to transmit the setting information to the specific entity'sdevice 110.

And, the specific entity's device 110 may display the settinginformation, to thereby allow the specific entity to confirm the settinginformation, and if the specific entity confirms and approves therelational information between the specific entity's DID and saidanother entity's DID, then the specific entity's device 110 maybroadcast the request for the registration of the relational informationto the blockchain network 200 at a step of S54.

Herein, the request for the registration of the relational informationmay include (1) the setting information transmitted from said anotherentity's device 120 and (2) the confirmation information where thespecific entity's device 110 may create the confirmation information byconfirming the relational information between the specific entity's DIDand said another entity's DID. And, the confirmation information mayinclude (1) the relational information and (2) the specific entity'ssignature value created by encrypting the relational information withthe specific entity's private key corresponding to the specific entity'sDID. As another example, if the setting information transmitted fromsaid another entity's device 120 is stored in the blockchain node 210,the confirmation information may be broadcast to the blockchain network200 as the request for the registration of the relational information.

Then, the blockchain node 210 may perform or support another device toperform a process of receiving the request for the registration of therelational information where the request is broadcast to the blockchainnetwork 200 by the specific entity's device 110, and a process ofverifying the request for the registration of the relational informationat a step of S55.

As one example, the blockchain node 210 may perform or support anotherdevice to perform a process of acquiring the specific entity's publickey from the blockchain network 200 by referring to the specificentity's DID. As another example, the blockchain node 210 may perform orsupport another device to perform a process of allowing the identitycontract to acquire the specific entity's public key from the blockchainnetwork 200 by referring to the specific entity's DID. And, theblockchain node 210 may perform or support another device to perform aprocess of verifying the confirmation information by decrypting thespecific entity's signature value, included in the confirmationinformation, with the specific entity's public key, to thereby verifythe request for the registration of the relational information. Herein,the confirmation information may be verified by determining whether therelational information acquired by decrypting the specific entity'ssignature value is identical to the relational information included inthe confirmation information.

Meanwhile, as another example different from verifying the request forthe registration of the relational information by the blockchain node210 itself, the blockchain node 210 may perform or support anotherdevice to perform a process of transmitting the request for theregistration of the relational information to the identity contract, tothereby allow the identity contract to verify the request for theregistration of the relational information.

Thereafter, the blockchain node 210 may perform or support anotherdevice to perform one of (i) a process of registering the relationalinformation in the blockchain network 200 as corresponding to thespecific entity's DID and said another entity's DID if the request forthe registration of the relational information is determined as verifiedby the blockchain node, at a step of S56, and (ii) a process of allowingthe identity contract to register the relational information in theblockchain network 200 as corresponding to the specific entity's DID andsaid another entity's DID if the request for the registration of therelational information is determined as verified by the identitycontract, at the step of S56.

On condition that the relational information on the relation between thespecific entity's DID and said another entity's DID have been registeredin the blockchain network 200 as above, in order to provide the specificentity with the service which is accessible with said another entity'sDID, the request for the service may be transmitted to the serviceproviding server 300 by using the specific entity's device 110 at a stepof S57. Herein, the request for the service may include the specificentity's signature value created by encrypting the request for theservice with the specific entity's private key corresponding to thespecific entity's DID.

Then, the service providing server 300 may verify the request for theservice, where the service is accessible with said another entity's DID,transmitted from the specific entity's device 110, at a step of S60.

As one example, the service providing server 300 may broadcast therequest for the specific entity's public key corresponding to thespecific entity's DID to the blockchain network 200 at a step of S58.Then, the blockchain node 210 may perform or support another device toperform (i) a process of acquiring the request for the specific entity'spublic key broadcast to the blockchain network 200, (ii) a process ofacquiring the specific entity's public key, corresponding to thespecific entity's DID, from the blockchain network 200 in response tothe request for the specific entity's public key, and (iii) a process oftransmitting the specific entity's public key, acquired from theblockchain network 200, to the service providing server 300 at a step ofS59. As another example, the blockchain node 210 may perform or supportanother device to perform (i) a process of allowing the identitycontract registered in the blockchain network 200 to acquire thespecific entity's public key from the blockchain network 200 byreferring to the specific entity's DID, and (ii) a process oftransmitting the specific entity's public key to the service providingserver 300 at the step of S59. And, the service providing server 300 mayverify the request for the service by decrypting the specific entity'ssignature value, which is included in the request for the service, withthe specific entity's public key transmitted from the blockchain node210, at a step of S60. Herein, the request for the service may beverified by determining whether the request for the service acquired bydecrypting the specific entity's signature value is identical to therequest for the service transmitted from the specific entity's device.

Thereafter, if the request for the service is determined as verified,the service providing server 300 may broadcast the request for therelational information to the blockchain network 200 at a step of S61.

Herein, the request for the relational information may include thespecific entity's DID or said another entity's DID.

And, the blockchain node 210 may perform or support another device toperform (i) a process of receiving the request for the relationalinformation broadcast to the blockchain network 200, (ii) in response tothe request for the relational information, one of (ii-1) a process ofacquiring the relational information from the blockchain network 200 byreferring to the specific entity's DID or said another entity's DID and(ii-2) a process of allowing the identity contract to acquire therelational information from the blockchain network 200 by referring tothe specific entity's DID or said another entity's DID, and (iii) aprocess of transmitting the relational information to the serviceproviding server 300 at a step of S62.

And, the service providing server 300 may confirm the relation betweenthe specific entity's DID and said another entity's DID by referring tothe relational information acquired from the blockchain node 210, at astep of S63.

Thereafter, if the relation between the specific entity's DID and saidanother entity's DID is confirmed by referring to the relationalinformation, the service accessible with said another entity's DID maybe provided to the specific entity's device 110 at a step of S64. As oneexample, if the relational information represents that “the specificentity's DID is the owner of said another entity's DID”, and if therequest for the service represents a log-on request using said anotherentity's DID, the service providing server 300 may confirm that thespecific entity's DID is the owner of said another entity's DID byreferring to the relational information, and may allow the specificentity's device 110 to log-on by using said another entity's DID.

FIG. 5 is a drawing schematically illustrating a method for providingthe relational DID service in accordance with still yet another exampleembodiment of the present disclosure. The method for providing therelational DID service in accordance with still yet another exampleembodiment of the present disclosure is described by referring to FIG. 5as follows. In the description below, the part easily deducible from theexplanation of FIGS. 2 and 3 will be omitted.

In order to set the relation with the specific entity, said anotherentity may broadcast the setting information to the blockchain network200 at a step of S71. Herein, the setting information may represent therelation between the specific entity and said another entity, where therelation may be set by using said another entity's device 120.

Herein, the setting information may include (1) the relationalinformation representing the relation between the specific entity's DIDand said another entity's DID, respectively corresponding to thespecific entity and said another entity, and (2) said another entity'ssignature value created by encrypting the relational information withsaid another entity's private key corresponding to said another entity'sDID. And the relational information may include information on relationsamong various entities, such as an IoT device and its owner, a parentand his/her child, an employee and his/her employer, a student andhis/her professor, etc. As one example, the relational information maybe set as representing that “the specific entity's DID is the owner ofsaid another entity's DID”.

Then, at least one blockchain node 210 in the blockchain network 200 mayreceive the setting information broadcast to the blockchain network 200,and may verify the received setting information at a step of S72.

As one example, the blockchain node 210 may perform or support anotherdevice to perform a process of acquiring said another entity's publickey from the blockchain network 200 by referring to said anotherentity's DID. As another example, the blockchain node 210 may perform orsupport another device to perform a process of allowing the identitycontract to acquire said another entity's public key from the blockchainnetwork 200 by referring to said another entity's DID. And, theblockchain node 210 may perform or support another device to perform aprocess of verifying the setting information by decrypting said anotherentity's signature value, included in the setting information, with saidanother entity's public key. Herein, the setting information may beverified by determining whether the relational information acquired bydecrypting said another entity's signature value is identical to therelational information included in the setting information. Meanwhile,as another example different from verifying the setting information bythe blockchain node 210 itself, the blockchain node 210 may perform orsupport another device to perform a process of transmitting the settinginformation to the identity contract, to thereby allow the identitycontract to verify the setting information.

Thereafter, if the setting information is determined as verified, theblockchain node 210 may perform or support another device to perform aprocess of transmitting the setting information, acquired from saidanother entity's device 120, to the specific entity's device 110 at astep of S73. Also, the blockchain node 210 may allow the identitycontract to transmit a verification result on the setting information tosaid another entity's device 120, to thereby allow said another entity'sdevice 120 to transmit the setting information to the specific entity'sdevice 110.

And, the specific entity's device 110 may display the settinginformation, to thereby allow the specific entity to confirm the settinginformation, and if the specific entity confirms and approves therelational information between the specific entity's DID and saidanother entity's DID, then the specific entity's device 110 maybroadcast the request for the registration of the relational informationto the blockchain network 200 at a step of S74.

Herein, the request for the registration of the relational informationmay include (1) the setting information transmitted from said anotherentity's device 120 and (2) the confirmation information where thespecific entity's device 110 may create the confirmation information byconfirming the relational information between the specific entity's DIDand said another entity's DID. And, the confirmation information mayinclude (1) the relational information and (2) the specific entity'ssignature value created by encrypting the relational information withthe specific entity's private key corresponding to the specific entity'sDID. As another example, if the setting information transmitted fromsaid another entity's device 120 is stored in the blockchain node 210,the confirmation information may be broadcast to the blockchain network200 as the request for the registration of the relational information.

Then, the blockchain node 210 may perform or support another device toperform a process of receiving the request for the registration of therelational information where the request is broadcast to the blockchainnetwork 200 by the specific entity's device 110, and a process ofverifying the request for the registration of the relational informationat a step of S75.

As one example, the blockchain node 210 may perform or support anotherdevice to perform a process of acquiring the specific entity's publickey from the blockchain network 200 by referring to the specificentity's DID. As another example, the blockchain node 210 may perform orsupport another device to perform a process of allowing the identitycontract to acquire the specific entity's public key from the blockchainnetwork 200 by referring to the specific entity's DID. And, theblockchain node 210 may perform or support another device to perform aprocess of verifying the confirmation information by decrypting thespecific entity's signature value, included in the confirmationinformation, with the specific entity's public key, to thereby verifythe request for the registration of the relational information. Herein,the confirmation information may be verified by determining whether therelational information acquired by decrypting the specific entity'ssignature value is identical to the relational information included inthe confirmation information.

Meanwhile, as another example different from verifying the request forthe registration of the relational information by the blockchain node210 itself, the blockchain node 210 may perform or support anotherdevice to perform a process of transmitting the request for theregistration of the relational information to the identity contract, tothereby allow the identity contract to verify the request for theregistration of the relational information.

Thereafter, the blockchain node 210 may perform or support anotherdevice to perform one of (i) a process of registering the relationalinformation in the blockchain network 200 as corresponding to thespecific entity's DID and said another entity's DID if the request forthe registration of the relational information is determined as verifiedby the blockchain node, at a step of S76, and (ii) a process of allowingthe identity contract to register the relational information in theblockchain network 200 as corresponding to the specific entity's DID andsaid another entity's DID if the request for the registration of therelational information is determined as verified by the identitycontract, at the step of S76.

On condition that the relational information on the relation between thespecific entity's DID and said another entity's DID have been registeredin the blockchain network 200 as above, in order to provide the specificentity with the service which is accessible with said another entity'sDID, the request for the service may be transmitted to the serviceproviding server 300 by using the specific entity's device 110 at a stepof S77. Herein, the request for the service may include the specificentity's signature value created by encrypting the request for theservice with the specific entity's private key corresponding to thespecific entity's DID.

Then, the service providing server 300 may verify the request for theservice, where the service is accessible with said another entity's DID,transmitted from the specific entity's device 110, at a step of S82.

As one example, in order to acquire the specific entity's public keycorresponding to the specific entity's DID, the specific entity's device300 may transmit the request for the specific entity's DID document,corresponding to the specific entity's DID, to the resolving server 400,at a step of S78. And, in response to the request for the specificentity's DID document from the service providing server 300, theresolving server 400 may broadcast the request for the specific entity'spublic information to the blockchain network 200 at a step of S79.Herein, the specific entity's public information may be registered inthe blockchain network 200 as corresponding to the specific entity's DIDand may include the relational information and the specific entity'spublic key corresponding to the specific entity's DID. Then, in responseto the request for the specific entity's public information, at leastone blockchain node 210 in the blockchain network 200 may perform orsupport another device to perform (i) a process of acquiring thespecific entity's public information, corresponding to the specificentity's DID, from the blockchain network 200, and (ii) a process oftransmitting the specific entity's public information, acquired from theblockchain network 200, to the resolving server 400 at a step of S80. Asanother example, the blockchain node 210 may perform or support anotherdevice to perform (i) a process of allowing the identity contractregistered in the blockchain network 200 to acquire the specificentity's public information from the blockchain network 200 by referringto the specific entity's DID, and (ii) a process of transmitting thespecific entity's public information to the resolving server 400. And,the resolving server 400 may modify the specific entity's publicinformation, transmitted from the blockchain node 210, into the specificentity's DID document, and may transmit the specific entity's DIDdocument to the service providing server 300 at a step of S81. And, theservice providing server 300 may acquire the specific entity's publickey from the specific entity's DID document which is transmitted fromthe resolving server 400, and may verify the request for the service bydecrypting the specific entity's signature value, which is included inthe request for the service, with the specific entity's public key, at astep of S82. Herein, the request for the service may be verified bydetermining whether the request for the service acquired by decryptingthe specific entity's signature value is identical to the request forthe service transmitted from the specific entity's device 110.

Thereafter, if the request for the service is determined as verified,the service providing server 300 may transmit the request for the DIDdocument to the resolving server 400 at a step of S83.

Herein, the request for the DID document may be at least one of therequest for the specific entity's DID document and the request for saidanother entity's DID document.

Then, in response to the request for the DID document from the serviceproviding server 300, the resolving server 400 may broadcast the requestfor the DID public information, corresponding to the request for the DIDdocument, to the blockchain network 200 at a step of S84.

Herein, the DID public information may include at least one of thespecific entity's public information and said another entity's publicinformation. And, the specific entity's public information may beregistered in the blockchain network 200 as corresponding to thespecific entity's DID and may include the relational information and thespecific entity's public key corresponding to the specific entity's DID.Also, said another entity's public information may be registered in theblockchain network 200 as corresponding to said another entity's DID andmay include the relational information and said another entity's publickey corresponding to said another entity's DID.

And, the blockchain node 210 may perform or support another device toperform (i) a process of receiving the request for the DID publicinformation broadcast to the blockchain network 200, (ii) in response tothe request for the DID public information, one of (ii-1) a process ofacquiring the DID public information from the blockchain network 200 byreferring to at least one of the specific entity's DID and said anotherentity's DID, and (ii-2) a process of allowing the identity contract toacquire the DID public information from the blockchain network 200 byreferring to at least one of the specific entity's DID and said anotherentity's DID, and (iii) a process of transmitting the DID publicinformation to the resolving server 400 at a step of S85.

Then, the resolving server 400 may modify the DID public informationinto the DID document, and may transmit the DID document to the serviceproviding server 300 at a step of S86.

And, the service providing server 300 may confirm the relation betweenthe specific entity's DID and said another entity's DID by referring tothe relational information acquired from the DID document, at a step ofS87.

Thereafter, if the relation between the specific entity's DID and saidanother entity's DID is confirmed by referring to the relationalinformation, the service accessible with said another entity's DID maybe provided to the specific entity's device 110 at a step of S88. As oneexample, if the relational information represents that “the specificentity's DID is the owner of said another entity's DID”, and if therequest for the service represents a log-on request using said anotherentity's DID, the service providing server 300 may confirm that thespecific entity's DID is the owner of said another entity's DID byreferring to the relational information, and may allow the specificentity's device 110 to log-on by using said another entity's DID.

The present disclosure has an effect of proving relations among theentities by registering the relations among the entities using the DIDs.

The present disclosure has another effect of providing various servicesby using the relations among the entities as a result of registering therelations among the entities using the DIDs.

The embodiments of the present disclosure as explained above can beimplemented in a form of executable program command through a variety ofcomputer means recordable to computer readable media. The computerreadable media may include solely or in combination, program commands,data files, and data structures. The program commands recorded to themedia may be components specially designed for the present disclosure ormay be usable to a skilled human in a field of computer software.Computer readable media include magnetic media such as hard disk, floppydisk, and magnetic tape, optical media such as CD-ROM and DVD,magneto-optical media such as floptical disk and hardware devices suchas ROM, RAM, and flash memory specially designed to store and carry outprogram commands. Program commands may include not only a machinelanguage code made by a complier but also a high level code that can beused by an interpreter etc., which is executed by a computer. Theaforementioned hardware device can work as more than a software moduleto perform the action of the present disclosure and they can do the samein the opposite case.

As seen above, the present disclosure has been explained by specificmatters such as detailed components, limited embodiments, and drawings.They have been provided only to help more general understanding of thepresent disclosure. It, however, will be understood by those skilled inthe art that various changes and modification may be made from thedescription without departing from the spirit and scope of thedisclosure as defined in the following claims.

Accordingly, the thought of the present disclosure must not be confinedto the explained embodiments, and the following patent claims as well aseverything including variations equal or equivalent to the patent claimspertain to the category of the thought of the present disclosure.

What is claimed is:
 1. A method for providing a relational DID(decentralized identifier) service, comprising steps of: (a0) (i) ablockchain node in a blockchain network performing or supporting anotherdevice to perform processes of registering a specific entity's DID inthe blockchain network and registering specific entity's publicinformation corresponding to the specific entity's DID in the blockchainnetwork in response to a request for registration of the specificentity's DID being broadcast from a specific entity's device to theblockchain network; and (ii) the blockchain node performing orsupporting another device to perform processes of registering anotherentity's DID in the blockchain network and registering another entity'spublic information corresponding to said another entity's DID in theblockchain network in response to a request for registration of saidanother entity's DID being broadcast from another entity's device to theblockchain network, wherein the specific entity's DID of the specificentity and said another entity's DID of said another entity aredifferent DIDs in the blockchain network; (a) in response to a requestfor registration of relational information being broadcast from thespecific entity's device to the blockchain network, wherein therelational information represents information on a relation between thespecific entity's DID of a specific entity and said another entity's DIDof another entity, wherein the relational information is selected fromthe group consisting of: the specific entity's DID of the specificentity being an owner of the another entity's DID of the another entity,an Internet of Things (IoT) device and its owner, a parent and a child,an employee and an employer, and a student and a professor, and whereinthe relational information is set by said another entity and confirmedby the specific entity, the blockchain node performing or supportinganother device to perform one of (i) a process of verifying the requestfor the registration of the relational information and (ii) a process oftransmitting the request for the registration of the relationalinformation to an identity contract registered in the blockchainnetwork, to thereby allow the identity contract to verify the requestfor the registration of the relational information; and (b) theblockchain node performing or supporting another device to perform oneof (i) a process of registering the relational information in theblockchain network as corresponding to the specific entity's DID andsaid another entity's DID in response to the request for theregistration of the relational information being determined as verifiedby the blockchain node, and (ii) a process of allowing the identitycontract to register the relational information in the blockchainnetwork as corresponding to the specific entity's DID and said anotherentity's DID in response to the request for the registration of therelational information being determined as verified by the identitycontract, wherein, at the step of (a), the request for the registrationof the relational information includes setting information andconfirmation information, wherein another entity's device correspondingto said another entity's DID creates the setting information by settinga relation between the specific entity's DID and said another entity'sDID, and wherein the specific entity's device creates the confirmationinformation by confirming the relation between the specific entity's DIDand said another entity's DID.
 2. The method of claim 1, furthercomprising a step of: (c) in response to a request for the relationalinformation being acquired from a service providing server whichreceived a request for a service transmitted from the specific entity'sdevice, wherein the service is accessible with said another entity's DIDor in response to a request for DID public information being acquiredfrom a resolving server which received a request for a DID document fromthe service providing server, wherein the request for the DID documentis at least one of a request for a specific entity's DID document and arequest for another entity's DID document, wherein the DID publicinformation includes at least one of specific entity's publicinformation and another entity's public information, wherein thespecific entity's public information is registered in the blockchainnetwork as corresponding to the specific entity's DID and includes therelational information and a specific entity's public key correspondingto the specific entity's DID, and wherein said another entity's publicinformation is registered in the blockchain network as corresponding tosaid another entity's DID and includes the relational information andanother entity's public key corresponding to said another entity's DID,the blockchain node performing or supporting another device to perform(1) one of (i) in response to the request for the relational informationfrom the service providing server, (i-1) a process of acquiring therelational information from the blockchain network by referring to thespecific entity's DID or said another entity's DID or a process ofallowing the identity contract to acquire the relational informationfrom the blockchain network by referring to the specific entity's DID orsaid another entity's DID, and (i-2) a process of transmitting therelational information to the service providing server, and (ii) inresponse to the request for the DID public information from theresolving server, (ii-1) a process of acquiring the DID publicinformation from the blockchain network by referring to at least one ofthe specific entity's DID and said another entity's DID or a process ofallowing the identity contract to acquire the DID public informationfrom the blockchain network by referring to at least one of the specificentity's DID and said another entity's DID, and (ii-2) a process ofallowing the resolving server to modify the DID public information intothe DID document and thus to transmit the DID document to the serviceproviding server, and as a result, (2) a process of allowing the serviceproviding server to (i) confirm a relation between the specific entity'sDID and said another entity's DID by referring to one of the relationalinformation acquired from the blockchain node and the relationalinformation acquired from the DID document, and (ii) in response to therelation between the specific entity's DID and said another entity's DIDbeing confirmed by using the relational information, provide the servicecorresponding to said another entity's DID to the specific entity'sdevice.
 3. The method of claim 2, wherein the request for the servicetransmitted from the specific entity's device includes a specificentity's signature value created by encrypting the request for theservice with a specific entity's private key corresponding to thespecific entity's DID, and wherein, in response to a request for thespecific entity's public key corresponding to the specific entity's DIDbeing acquired from the service providing server or in response to arequest for the specific entity's public information being acquired fromthe resolving server which received the request for the specificentity's DID document from the service providing server, the blockchainnode performs or supports another device to perform (1) one of (i) inresponse to the request for the specific entity's public key from theservice providing server, (i-1) a process of acquiring the specificentity's public key corresponding to the specific entity's DID from theblockchain network by referring to the specific entity's DID or aprocess of allowing the identity contract to acquire the specificentity's public key from the blockchain network by referring to thespecific entity's DID, and (i-2) a process of transmitting the specificentity's public key to the service providing server and (ii) in responseto the request for the specific entity's public information from theresolving server, (ii-1) a process of acquiring the specific entity'spublic information from the blockchain network by referring to thespecific entity's DID or a process of allowing the identity contract toacquire the specific entity's public information from the blockchainnetwork by referring to the specific entity's DID, and (ii-2) a processof allowing the resolving server to modify the specific entity's publicinformation into the specific entity's DID document and thus to transmitthe specific entity's DID document to the service providing server, andas a result, (2) a process of allowing the service providing server to(i) verify the specific entity's signature value by decrypting thespecific entity's signature value with the specific entity's public keyacquired from the blockchain node or from the specific entity's DIDdocument, and (ii) in response to the specific entity's signature valuebeing determined as verified, broadcast the request for the relationalinformation to the blockchain network.
 4. The method of claim 1, whereinthe setting information includes (1) the relational informationrepresenting a relation between the specific entity's DID and saidanother entity's DID, and (2) another entity's signature value createdby encrypting the relational information with another entity's privatekey corresponding to said another entity's DID, and wherein theconfirmation information includes (1) the relational information and (2)a specific entity's signature value created by encrypting the relationalinformation with a specific entity's private key corresponding to thespecific entity's DID, and wherein the blockchain node performs orsupports another device to perform (i) (i-1) a process of acquiring aspecific entity's public key corresponding to the specific entity's DIDand another entity's public key corresponding to said another entity'sDID from the blockchain network by referring to the specific entity'sDID and said another entity's DID or (i-2) a process of allowing theidentity contract to acquire the specific entity's public key and saidanother entity's public key from the blockchain network by referring tothe specific entity's DID and said another entity's DID, (ii) a processof verifying the setting information by decrypting said another entity'ssignature value with said another entity's public key, and (iii) aprocess of verifying the confirmation information by decrypting thespecific entity's signature value with the specific entity's public key,to thereby verify the request for the registration of the relationalinformation.
 5. The method of claim 4, wherein, in response to a requestfor said another entity's public key being acquired from the specificentity's device which received the setting information transmitted fromsaid another entity's device wherein said another entity's public keycorresponds to said another entity's DID or in response to a request foranother entity's public information being acquired from a resolvingserver which received a request for another entity's DID document fromthe specific entity's device wherein said another entity's publicinformation is registered in the blockchain network as corresponding tosaid another entity's DID and includes the relational information andanother entity's public key corresponding to said another entity's DID,the blockchain node performs or supports another device to perform (1)one of (i) in response to the request for said another entity's publickey from the specific entity's device, (i-1) a process of acquiring saidanother entity's public key from the blockchain network by referring tosaid another entity's DID or a process of allowing the identity contractto acquire said another entity's public key from the blockchain networkby referring to said another entity's DID, and (i-2) a process oftransmitting said another entity's public key to the specific entity'sdevice, and (ii) in response to the request for said another entity'spublic information from the resolving server, (ii-1) a process ofacquiring another entity's public information from the blockchainnetwork by referring to said another entity's DID or a process ofallowing the identity contract to acquire said another entity's publicinformation from the blockchain network by referring to said anotherentity's DID, and (ii-2) a process of allowing the resolving server tomodify said another entity's public information into said anotherentity's DID document and thus to transmit said another entity's DIDdocument to the specific entity's device, and as a result, (2) a processof allowing the specific entity's device to (i) verify the settinginformation by decrypting said another entity's signature value withsaid another entity's public key acquired from the blockchain node orfrom said another entity's DID document, and (ii) in response to thesetting information being determined as verified, broadcast the requestfor the registration of the relational information to the blockchainnetwork.
 6. The method of claim 4, wherein, in response to the settinginformation broadcast from said another entity's device to theblockchain network being acquired, the blockchain node performs orsupports another device to perform a process of transmitting the settinginformation to the specific entity's device or a process of allowing theidentity contract to transmit the setting information to the specificentity's device, to thereby allow the specific entity's device tobroadcast the request for the registration of the relational informationto the blockchain network in response to a verification result on thesetting information which is verified by the specific entity's deviceand thus acquire the request for the registration of the relationalinformation.
 7. The method of claim 1, wherein, in response to thesetting information being broadcast from said another entity's device tothe blockchain network, the blockchain node performs or supports anotherdevice to perform (i) a process of acquiring another entity's public keyfrom the blockchain network by referring to said another entity's DID ora process of allowing the identity contract to acquire said anotherentity's public key from the blockchain network by referring to saidanother entity's DID, (ii) a process of verifying the settinginformation by decrypting said another entity's signature value withsaid another entity's public key, and (iii) in response to the settinginformation being determined as verified, a process of transmitting thesetting information to the specific entity's device or a process ofallowing the identity contract to transmit a verification result on thesetting information to said another entity's device and thus to allowsaid another entity's device to transmit the setting information to thespecific entity's device, and wherein, in response to the confirmationinformation being broadcast from the specific entity's device to theblockchain network, the blockchain node performs or supports anotherdevice to perform (i) a process of acquiring a specific entity's publickey from the blockchain network by referring to the specific entity'sDID, or a process of allowing the identity contract to acquire thespecific entity's public key from the blockchain network by referring tothe specific entity's DID, and (ii) a process of verifying theconfirmation information by decrypting the specific entity's signaturevalue with the specific entity's public key.
 8. A blockchain node in ablockchain network for providing a relational (decentralized identifier)service, comprising: at least one memory that stores instructions; andat least one processor configured to execute the instructions to performor support another device to perform: (I0) (i) processes of registeringa specific entity's DID in the blockchain network and registeringspecific entity's public information corresponding to the specificentity's DID in the blockchain network in response to a request forregistration of the specific entity's DID being broadcast from aspecific entity's device to the blockchain network; and (ii) processesof registering another entity's DID in the blockchain network andregistering another entity's public information corresponding to saidanother entity's DID in the blockchain network in response to a requestfor registration of said another entity's DID being broadcast fromanother entity's device to the blockchain network, wherein the specificentity's DID of the specific entity and said another entity's DID ofsaid another entity are different DIDs in the blockchain network; (I) inresponse to a request for registration of relational information beingbroadcast from the specific entity's device to the blockchain network,wherein the relational information represents information on a relationbetween the specific entity's DID of a specific entity and said anotherentity's DID of another entity, wherein the relational information isselected from the group consisting of: the specific entity's DID of thespecific entity being an owner of the another entity's DID of theanother entity, an Internet of Things (IoT) device and its owner, aparent and a child, an employee and an employer, and a student and aprofessor, and wherein the relational information is set by said anotherentity and confirmed by the specific entity, one of (i) a process ofverifying the request for the registration of the relational informationand (ii) a process of transmitting the request for the registration ofthe relational information to an identity contract registered in theblockchain network, to thereby allow the identity contract to verify therequest for the registration of the relational information, and (II) oneof (i) a process of registering the relational information in theblockchain network as corresponding to the specific entity's DID andsaid another entity's DID in response to the request for theregistration of the relational information being determined as verifiedby the blockchain node, and (ii) a process of allowing the identitycontract to register the relational information in the blockchainnetwork as corresponding to the specific entity's DID and said anotherentity's DID in response to the request for the registration of therelational information being determined as verified by the identitycontract, wherein, at the process of (I), the request for theregistration of the relational information includes setting informationand confirmation information, wherein another entity's devicecorresponding to said another entity's DID creates the settinginformation by setting a relation between the specific entity's DID andsaid another entity's DID, and wherein the specific entity's devicecreates the confirmation information by confirming the relation betweenthe specific entity's DID and said another entity's DID.
 9. Theblockchain node of claim 8, wherein the processor further performs orsupports another device to perform: (III) in response to a request forthe relational information being acquired from a service providingserver which received a request for a service transmitted from thespecific entity's device wherein the service is accessible with saidanother entity's DID or in response to a request for DID publicinformation being acquired from a resolving server which received arequest for a DID document from the service providing server, whereinthe request for the DID document is at least one of a request for aspecific entity's DID document and a request for another entity's DIDdocument, wherein the DID public information includes at least one ofspecific entity's public information and another entity's publicinformation, wherein the specific entity's public information isregistered in the blockchain network as corresponding to the specificentity's DID and includes the relational information and a specificentity's public key corresponding to the specific entity's DID, andwherein said another entity's public information is registered in theblockchain network as corresponding to said another entity's DID andincludes the relational information and another entity's public keycorresponding to said another entity's DID, (1) one of (i) in responseto the request for the relational information from the service providingserver, (i-1) a process of acquiring the relational information from theblockchain network by referring to the specific entity's DID or saidanother entity's DID or a process of allowing the identity contract toacquire the relational information from the blockchain network byreferring to the specific entity's DID or said another entity's DID, and(i-2) a process of transmitting the relational information to theservice providing server, and (ii) in response to the request for theDID public information from the resolving server, (ii-1) a process ofacquiring the DID public information from the blockchain network byreferring to at least one of the specific entity's DID and said anotherentity's DID or a process of allowing the identity contract to acquirethe DID public information from the blockchain network by referring toat least one of the specific entity's DID and said another entity's DID,and (ii-2) a process of allowing the resolving server to modify the DIDpublic information into the DID document and thus to transmit the DIDdocument to the service providing server, and as a result, (2) a processof allowing the service providing server to (i) confirm a relationbetween the specific entity's DID and said another entity's DID byreferring to one of the relational information acquired from theblockchain node and the relational information acquired from the DIDdocument, and (ii) in response to the relation between the specificentity's DID and said another entity's DID being confirmed by using therelational information, provide the service corresponding to saidanother entity's DID to the specific entity's device.
 10. The blockchainnode of claim 9, wherein the request for the service transmitted fromthe specific entity's device includes a specific entity's signaturevalue created by encrypting the request for the service with a specificentity's private key corresponding to the specific entity's DID, andwherein, in response to a request for the specific entity's public keycorresponding to the specific entity's DID being acquired from theservice providing server or in response to a request for the specificentity's public information being acquired from the resolving serverwhich received the request for the specific entity's DID document fromthe service providing server, the processor performs or supports anotherdevice to perform (1) one of (i) in response to the request for thespecific entity's public key from the service providing server, (i-1) aprocess of acquiring the specific entity's public key corresponding tothe specific entity's DID from the blockchain network by referring tothe specific entity's DID or a process of allowing the identity contractto acquire the specific entity's public key from the blockchain networkby referring to the specific entity's DID, and (i-2) a process oftransmitting the specific entity's public key to the service providingserver and (ii) in response to the request for the specific entity'spublic information from the resolving server, (ii-1) a process ofacquiring the specific entity's public information from the blockchainnetwork by referring to the specific entity's DID or a process ofallowing the identity contract to acquire the specific entity's publicinformation from the blockchain network by referring to the specificentity's DID, and (ii-2) a process of allowing the resolving server tomodify the specific entity's public information into the specificentity's DID document and thus to transmit the specific entity's DIDdocument to the service providing server, and as a result, (2) a processof allowing the service providing server to (i) verify the specificentity's signature value by decrypting the specific entity's signaturevalue with the specific entity's public key acquired from the blockchainnode or from the specific entity's DID document, and (ii) in response tothe specific entity's signature value being determined as verified,broadcast the request for the relational information to the blockchainnetwork.
 11. The blockchain node of claim 8, wherein the settinginformation includes (1) the relational information representing arelation between the specific entity's DID and said another entity'sDID, and (2) another entity's signature value created by encrypting therelational information with another entity's private key correspondingto said another entity's DID, and wherein the confirmation informationincludes (1) the relational information and (2) a specific entity'ssignature value created by encrypting the relational information with aspecific entity's private key corresponding to the specific entity'sDID, and wherein the processor performs or supports another device toperform (i) (i-1) a process of acquiring a specific entity's public keycorresponding to the specific entity's DID and another entity's publickey corresponding to said another entity's DID from the blockchainnetwork by referring to the specific entity's DID and said anotherentity's DID or (i-2) a process of allowing the identity contract toacquire the specific entity's public key and said another entity'spublic key from the blockchain network by referring to the specificentity's DID and said another entity's DID, (ii) a process of verifyingthe setting information by decrypting said another entity's signaturevalue with said another entity's public key, and (iii) a process ofverifying the confirmation information by decrypting the specificentity's signature value with the specific entity's public key, tothereby verify the request for the registration of the relationalinformation.
 12. The blockchain node of claim 11, wherein, in responseto a request for said another entity's public key being acquired fromthe specific entity's device which received the setting informationtransmitted from said another entity's device wherein said anotherentity's public key corresponds to said another entity's DID or inresponse to a request for another entity's public information beingacquired from a resolving server which received a request for anotherentity's DID document from the specific entity's device wherein saidanother entity's public information is registered in the blockchainnetwork as corresponding to said another entity's DID and includes therelational information and another entity's public key corresponding tosaid another entity's DID, the processor performs or supports anotherdevice to perform (1) one of (i) in response to the request for saidanother entity's public key from the specific entity's device, (i-1) aprocess of acquiring said another entity's public key from theblockchain network by referring to said another entity's DID or aprocess of allowing the identity contract to acquire said anotherentity's public key from the blockchain network by referring to saidanother entity's DID, and (i-2) a process of transmitting said anotherentity's public key to the specific entity's device, and (ii) inresponse to the request for said another entity's public informationfrom the resolving server, (ii-1) a process of acquiring anotherentity's public information from the blockchain network by referring tosaid another entity's DID or a process of allowing the identity contractto acquire said another entity's public information from the blockchainnetwork by referring to said another entity's DID, and (ii-2) a processof allowing the resolving server to modify said another entity's publicinformation into said another entity's DID document and thus to transmitsaid another entity's DID document to the specific entity's device, andas a result, (2) a process of allowing the specific entity's device to(i) verify the setting information by decrypting said another entity'ssignature value with said another entity's public key acquired from theblockchain node or from said another entity's DID document, and (ii) inresponse to the setting information being determined as verified,broadcast the request for the registration of the relational informationto the blockchain network.
 13. The blockchain node of claim 11, wherein,in response to the setting information broadcast from said anotherentity's device to the blockchain network being acquired, the processorperforms or supports another device to perform a process of transmittingthe setting information to the specific entity's device or a process ofallowing the identity contract to transmit the setting information tothe specific entity's device, to thereby allow the specific entity'sdevice to broadcast the request for the registration of the relationalinformation to the blockchain network in response to a verificationresult on the setting information which is verified by the specificentity's device and thus acquire the request for the registration of therelational information.
 14. The blockchain node of claim 8, wherein, inresponse to the setting information being broadcast from said anotherentity's device to the blockchain network, the processor performs orsupports another device to perform (i) a process of acquiring anotherentity's public key from the blockchain network by referring to saidanother entity's DID or a process of allowing the identity contract toacquire said another entity's public key from the blockchain network byreferring to said another entity's DID, (ii) a process of verifying thesetting information by decrypting said another entity's signature valuewith said another entity's public key, and (iii) in response to thesetting information being determined as verified, a process oftransmitting the setting information to the specific entity's device ora process of allowing the identity contract to transmit a verificationresult on the setting information to said another entity's device andthus to allow said another entity's device to transmit the settinginformation to the specific entity's device, and wherein, in response tothe confirmation information being broadcast from the specific entity'sdevice to the blockchain network, the processor performs or supportsanother device to perform (i) a process of acquiring a specific entity'spublic key from the blockchain network by referring to the specificentity's DID, or a process of allowing the identity contract to acquirethe specific entity's public key from the blockchain network byreferring to the specific entity's DID, and (ii) a process of verifyingthe confirmation information by decrypting the specific entity'ssignature value with the specific entity's public key.